NAME¶
XPASet - send data to one or more XPA servers
SYNOPSIS¶
#include <xpa.h>
int XPASet(XPA xpa,
char *template, char *paramlist, char *mode,
char *buf, size_t len, char **names, char **messages,
int n);
DESCRIPTION¶
Send data to one or more XPA servers whose class:name identifier matches the
specified template.
A template of the form "class1:name1" is sent to the XPA name server,
which returns a list of at most n matching XPA servers. A connection is
established with each of these servers and the paramlist string is passed to
the server as the data transfer request is initiated. If an XPA struct is
passed to the call, the persistent connections are updated as described above.
Otherwise, temporary connections are made to the servers (which will be closed
when the call completes).
The
XPASet() routine transfers data from buf to the XPA servers. The
length of buf (in bytes) should be placed in the len variable.
A string containing the class:name and ip:port of each of these server is
returned in the name array. If a given server returned an error or the server
callback sends a message back to the client, then the message will be stored
in the associated element of the messages array. NB: if specified, the name
and messages arrays must be of size n or greater.
The returned message string will be of the form:
XPA$ERROR [error] (class:name ip:port)
or
XPA$MESSAGE [message] (class:name ip:port)
The return value will contain the actual number of servers that were processed.
This value thus will hold the number of valid entries in the names and
messages arrays, and can be used to loop through these arrays. In names and/or
messages is NULL, no information is passed back in that particular array.
The mode string is of the form: "key1=value1,key2=value2,..." The
following keywords are recognized:
key value default explanation
------ -------- -------- -----------
ack true/false true if false, don't wait for ack from server (after callback completes)
verify true/false false send buf from XPASet[Fd] to stdout
doxpa true/false true client processes xpa requests
The ack keyword is useful in cases where one does not want to wait for the
server to complete, e.g. if a lot of processing needs to be done by the server
on the passed data or when the success of the server operation is not relevant
to the client.
Normally, an XPA client will process incoming XPA server requests while awaiting
the completion of the client request. Setting this variable to
"false" will prevent XPA server requests from being processed by the
client.
Example -
#include <xpa.h>
#define NXPA 10
int i, got;
size_t len;
char *buf;
char *names[NXPA];
char *messages[NXPA];
...
[fill buf with data and set len to the length, in bytes, of the data]
...
/* send data to all access points */
got = XPASet(NULL, "ds9", "fits", NULL, buf, len, names, messages, NXPA);
/* error processing */
for(i=0; i<got; i++){
if( messages[i] ){
fprintf(stderr, "ERROR: %s (%s)\n", messages[i], names[i]);
}
if( names[i] ) free(names[i]);
if( messages[i] ) free(messages[i]);
}
SEE ALSO¶
See
xpa(7) for a list of XPA help pages